Total Synthesis of Lycogarubin C and Lycogalic Acid A

Lycogarubin C and lycogalic acid A are key marine natural products which are used in studies on inhibitor of DNA Topoisomerase-I. With (but-3-ynyloxy)(tert-butyl)dimethylsilane as starting material, lycogarubin C was prepared in the process with 8 steps, via hetero-/retro-Diels-Alder reaction, reduction of 1,2-diazine, Swern oxidation, and Fischer indole synthesis as the key reactions, and lycogalic acid A was also obtained in the reaction of lycogarubin C with potassium hydroxide.